1. Field of the Invention
The invention relates to an electrically insulating encapsulating composition consisting of a mixture of a resin and an inorganic filler for semiconductor arrangements.
2. Description of the Prior Art
Such encapsulating compositions for enclosing semiconductor arrangements such as discrete semiconductors or integrated circuits, are known, for instance, from German Pat. No. 17 89 053, from German Published Non-Prosecuted Application No. 21 48 690 and German Published Non-Prosecuted Application No. 21 64 100. Examples of resins which can be used are for instance, silicone resins as described in the journal "Electronik-praxis", No. 3/4, Mar. 26, 1968, pages 21-24, and epoxy resins, as is known from, for instance, Circuits Manufacturing, August 1977, pages 29-31. Quartz sand or quartz metal are, for instance, used as inorganic fillers.
If large-scale integrated circuits, for instance, semiconductor memories such as 16k or in particular 64k RAM's (Random Access Memories) are enclosed by such encapsulating compositions or provided with ceramic housings, the natural content of contaminating traces of radioactive thorium and uranium in the ceramic housings or in the inorganic filler causes so-called "soft-error" failures through alpha radiation.
As is known from Electronics, Sept. 11, 1980, pages 41 and 42, these failures can be avoided by covering the semiconductor chip with a thin silicone or polyimide layer, since these layers sufficiently reduce the energy of the alpha radiation coming from the filler or the ceramic housing. Such a covering of the semiconductor chip, however, is not without problems since it can have a negative effect on the tightness of the component housings and the electrical stability of the components. In particular, the different coefficients of expansion of the semiconductor base material (silicon, germanium or a II-V compound) and of the covering film easily lead to torn off contacts of the terminals (nail heads, etc.) which connect the semiconductor chip and the terminal contact pins.